Regulation of RNA sensing and viral restriction by RNA structures

项目总结 委内瑞拉马脑炎病毒(VEEV)是一种单链正义RNA病毒，由 蚊子，并负责周期性的流行性/流行性脑炎暴发，在马和 人类。先天和干扰素反应是防止复制和传播的关键障碍 许多病毒病原体，包括甲型病毒，如VEEV。结果，病毒进化成了多样化的 抑制或逃避先天免疫反应的机制以及抗病毒效应物，如干扰素刺激 基因(ISG)。已知RNA结构调节基本的病毒过程(例如，病毒RNA转录和 然而，病毒RNA结构在形成对病毒的先天免疫反应中所起的作用是 未得到充分研究。我们以前已经证明，甲型病毒在其5‘-未翻译的区域内编码稳定的结构 区域(5‘-UTR)对拮抗Ifit1是关键的，Ifit1是限制非自身RNA的重要ISG。我们有 还表明3‘-UTR中的RNA结构在调节IFIT2对病毒RNA的识别方面是重要的。 最近我们发现，3‘-非编码区和E1区的RNA结构可调节毒力和无毒病毒的复制 巨噬细胞中的Veev，是VEEV体内感染的重要靶点。这个项目的总体目标是 建议：1)描述强毒和无毒VEEV中调控E1RNA结构决定因素 巨噬细胞复制，2)定义E1结构决定因素如何将限制性商业惯例招募到病毒基因组和 这对宿主先天免疫反应的影响，3)确定巨噬细胞复制适合性如何有助于 VEEV编码强毒和无毒RNA结构在体内的不同致病机制，以及4)如何定义 巨噬细胞复制的适合性塑造了体内的先天免疫反应。这些研究的结果将提供 对VEEV致病和致病变异出现的新机制的关键洞察。这将会有 对我们理解病毒的出现和基于RNA的疗法的发展具有广泛的意义。

PROJECT SUMMARY Venezuelan equine encephalitis virus (VEEV) is a single-stranded positive-sense RNA virus transmitted by mosquitoes and is responsible for periodic epizootic/epidemic outbreaks of encephalitis in both horses and humans. The innate and interferon (IFN) responses are critical barriers for preventing the replication and spread of many viral pathogens including alphaviruses such as VEEV. As a result, viruses have evolved diverse mechanisms to inhibit or escape the innate immune response as well as antiviral effectors such as IFN-stimulated genes (ISGs). RNA structures are known to regulate basic viral processes (e.g. viral RNA transcription and translation), however, the role that viral RNA structure plays in shaping innate immune responses to viruses is understudied. We have previously shown that alphaviruses encode stable structures within their 5’-untranslated region (5’-UTR) that are critical for antagonizing IFIT1, an ISG important in restriction of non-self RNA. We have also shown that RNA structures in the 3’-UTR are important in modulating recognition of viral RNA by IFIT2. Recently we have shown that RNA structures in the 3’-UTR and E1 modulate replication of virulent and avirulent VEEV in macrophages, which are important targets of VEEV infection in vivo. The broad objectives of this proposal are to: 1) delineate E1 RNA structural determinants in virulent and avirulent VEEV that regulate macrophage replication, 2) define how E1 structural determinants recruit RBPs to the viral genome and the impact of this on host innate immune responses, 3) Define how macrophage replication fitness contributes to the differential pathogenesis in vivo of VEEV encoding virulent and avirulent RNA structures, and 4) Define how macrophage replication fitness shapes innate immune responses in vivo. Findings from these studies will provide key insight into novel mechanisms of VEEV pathogenesis and emergence of pathogenic variants. This will have broad implications for our understanding of viral emergence and development of RNA-based therapeutics.